zlib.c

嵌入式ARM的一些源代码

/* If BMAX needs to be larger than 16, then h and x[] should be uLong. */
#define BMAX 15         /* maximum bit length of any code */
#define N_MAX 288       /* maximum number of codes in any set */

#ifdef DEBUG_ZLIB
  uInt inflate_hufts;
#endif

local int huft_build(b, n, s, d, e, t, m, zs)
uIntf *b;               /* code lengths in bits (all assumed <= BMAX) */
uInt n;                 /* number of codes (assumed <= N_MAX) */
uInt s;                 /* number of simple-valued codes (0..s-1) */
uIntf *d;               /* list of base values for non-simple codes */
uIntf *e;               /* list of extra bits for non-simple codes */  
inflate_huft * FAR *t;  /* result: starting table */
uIntf *m;               /* maximum lookup bits, returns actual */
z_stream *zs;           /* for zalloc function */
/* Given a list of code lengths and a maximum table size, make a set of
   tables to decode that set of codes.  Return Z_OK on success, Z_BUF_ERROR
   if the given code set is incomplete (the tables are still built in this
   case), Z_DATA_ERROR if the input is invalid (all zero length codes or an
   over-subscribed set of lengths), or Z_MEM_ERROR if not enough memory. */
{

  uInt a;                       /* counter for codes of length k */
  uInt c[BMAX+1];               /* bit length count table */
  uInt f;                       /* i repeats in table every f entries */
  int g;                        /* maximum code length */
  int h;                        /* table level */
  register uInt i;              /* counter, current code */
  register uInt j;              /* counter */
  register int k;               /* number of bits in current code */
  int l;                        /* bits per table (returned in m) */
  register uIntf *p;            /* pointer into c[], b[], or v[] */
  inflate_huft *q;              /* points to current table */
  struct inflate_huft_s r;      /* table entry for structure assignment */
  inflate_huft *u[BMAX];        /* table stack */
  uInt v[N_MAX];                /* values in order of bit length */
  register int w;               /* bits before this table == (l * h) */
  uInt x[BMAX+1];               /* bit offsets, then code stack */
  uIntf *xp;                    /* pointer into x */
  int y;                        /* number of dummy codes added */
  uInt z;                       /* number of entries in current table */


  /* Generate counts for each bit length */
  p = c;
#define C0 *p++ = 0;
#define C2 C0 C0 C0 C0
#define C4 C2 C2 C2 C2
  C4                            /* clear c[]--assume BMAX+1 is 16 */
  p = b;  i = n;
  do {
    c[*p++]++;                  /* assume all entries <= BMAX */
  } while (--i);
  if (c[0] == n)                /* null input--all zero length codes */
  {
    *t = (inflate_huft *)Z_NULL;
    *m = 0;
    return Z_OK;
  }


  /* Find minimum and maximum length, bound *m by those */
  l = *m;
  for (j = 1; j <= BMAX; j++)
    if (c[j])
      break;
  k = j;                        /* minimum code length */
  if ((uInt)l < j)
    l = j;
  for (i = BMAX; i; i--)
    if (c[i])
      break;
  g = i;                        /* maximum code length */
  if ((uInt)l > i)
    l = i;
  *m = l;


  /* Adjust last length count to fill out codes, if needed */
  for (y = 1 << j; j < i; j++, y <<= 1)
    if ((y -= c[j]) < 0)
      return Z_DATA_ERROR;
  if ((y -= c[i]) < 0)
    return Z_DATA_ERROR;
  c[i] += y;


  /* Generate starting offsets into the value table for each length */
  x[1] = j = 0;
  p = c + 1;  xp = x + 2;
  while (--i) {                 /* note that i == g from above */
    *xp++ = (j += *p++);
  }


  /* Make a table of values in order of bit lengths */
  p = b;  i = 0;
  do {
    if ((j = *p++) != 0)
      v[x[j]++] = i;
  } while (++i < n);


  /* Generate the Huffman codes and for each, make the table entries */
  x[0] = i = 0;                 /* first Huffman code is zero */
  p = v;                        /* grab values in bit order */
  h = -1;                       /* no tables yet--level -1 */
  w = -l;                       /* bits decoded == (l * h) */
  u[0] = (inflate_huft *)Z_NULL;        /* just to keep compilers happy */
  q = (inflate_huft *)Z_NULL;   /* ditto */
  z = 0;                        /* ditto */

  /* go through the bit lengths (k already is bits in shortest code) */
  for (; k <= g; k++)
  {
    a = c[k];
    while (a--)
    {
      /* here i is the Huffman code of length k bits for value *p */
      /* make tables up to required level */
      while (k > w + l)
      {
        h++;
        w += l;                 /* previous table always l bits */

        /* compute minimum size table less than or equal to l bits */
        z = (z = g - w) > (uInt)l ? l : z;      /* table size upper limit */
        if ((f = 1 << (j = k - w)) > a + 1)     /* try a k-w bit table */
        {                       /* too few codes for k-w bit table */
          f -= a + 1;           /* deduct codes from patterns left */
          xp = c + k;
          if (j < z)
            while (++j < z)     /* try smaller tables up to z bits */
            {
              if ((f <<= 1) <= *++xp)
                break;          /* enough codes to use up j bits */
              f -= *xp;         /* else deduct codes from patterns */
            }
        }
        z = 1 << j;             /* table entries for j-bit table */

        /* allocate and link in new table */
        if ((q = (inflate_huft *)ZALLOC
             (zs,z + 1,sizeof(inflate_huft))) == Z_NULL)
        {
          if (h)
            inflate_trees_free(u[0], zs);
          return Z_MEM_ERROR;   /* not enough memory */
        }
	q->word.Nalloc = z + 1;
#ifdef DEBUG_ZLIB
        inflate_hufts += z + 1;
#endif
        *t = q + 1;             /* link to list for huft_free() */
        *(t = &(q->next)) = Z_NULL;
        u[h] = ++q;             /* table starts after link */

        /* connect to last table, if there is one */
        if (h)
        {
          x[h] = i;             /* save pattern for backing up */
          r.bits = (Byte)l;     /* bits to dump before this table */
          r.exop = (Byte)j;     /* bits in this table */
          r.next = q;           /* pointer to this table */
          j = i >> (w - l);     /* (get around Turbo C bug) */
          u[h-1][j] = r;        /* connect to last table */
        }
      }

      /* set up table entry in r */
      r.bits = (Byte)(k - w);
      if (p >= v + n)
        r.exop = 128 + 64;      /* out of values--invalid code */
      else if (*p < s)
      {
        r.exop = (Byte)(*p < 256 ? 0 : 32 + 64);     /* 256 is end-of-block */
        r.base = *p++;          /* simple code is just the value */
      }
      else
      {
        r.exop = (Byte)e[*p - s] + 16 + 64; /* non-simple--look up in lists */
        r.base = d[*p++ - s];
      }

      /* fill code-like entries with r */
      f = 1 << (k - w);
      for (j = i >> w; j < z; j += f)
        q[j] = r;

      /* backwards increment the k-bit code i */
      for (j = 1 << (k - 1); i & j; j >>= 1)
        i ^= j;
      i ^= j;

      /* backup over finished tables */
      while ((i & ((1 << w) - 1)) != x[h])
      {
        h--;                    /* don't need to update q */
        w -= l;
      }
    }
  }


  /* Return Z_BUF_ERROR if we were given an incomplete table */
  return y != 0 && g != 1 ? Z_BUF_ERROR : Z_OK;
}


local int inflate_trees_bits(c, bb, tb, z)
uIntf *c;               /* 19 code lengths */
uIntf *bb;              /* bits tree desired/actual depth */
inflate_huft * FAR *tb; /* bits tree result */
z_stream *z;            /* for zfree function */
{
  int r;

  r = huft_build(c, 19, 19, (uIntf*)Z_NULL, (uIntf*)Z_NULL, tb, bb, z);
  if (r == Z_DATA_ERROR)
    z->msg = "oversubscribed dynamic bit lengths tree";
  else if (r == Z_BUF_ERROR)
  {
    inflate_trees_free(*tb, z);
    z->msg = "incomplete dynamic bit lengths tree";
    r = Z_DATA_ERROR;
  }
  return r;
}


local int inflate_trees_dynamic(nl, nd, c, bl, bd, tl, td, z)
uInt nl;                /* number of literal/length codes */
uInt nd;                /* number of distance codes */
uIntf *c;               /* that many (total) code lengths */
uIntf *bl;              /* literal desired/actual bit depth */
uIntf *bd;              /* distance desired/actual bit depth */
inflate_huft * FAR *tl; /* literal/length tree result */
inflate_huft * FAR *td; /* distance tree result */
z_stream *z;            /* for zfree function */
{
  int r;

  /* build literal/length tree */
  if ((r = huft_build(c, nl, 257, cplens, cplext, tl, bl, z)) != Z_OK)
  {
    if (r == Z_DATA_ERROR)
      z->msg = "oversubscribed literal/length tree";
    else if (r == Z_BUF_ERROR)
    {
      inflate_trees_free(*tl, z);
      z->msg = "incomplete literal/length tree";
      r = Z_DATA_ERROR;
    }
    return r;
  }

  /* build distance tree */
  if ((r = huft_build(c + nl, nd, 0, cpdist, cpdext, td, bd, z)) != Z_OK)
  {
    if (r == Z_DATA_ERROR)
      z->msg = "oversubscribed literal/length tree";
    else if (r == Z_BUF_ERROR) {
#ifdef PKZIP_BUG_WORKAROUND
      r = Z_OK;
    }
#else
      inflate_trees_free(*td, z);
      z->msg = "incomplete literal/length tree";
      r = Z_DATA_ERROR;
    }
    inflate_trees_free(*tl, z);
    return r;
#endif
  }

  /* done */
  return Z_OK;
}


/* build fixed tables only once--keep them here */
local int fixed_lock = 0;
local int fixed_built = 0;
#define FIXEDH 530      /* number of hufts used by fixed tables */
local uInt fixed_left = FIXEDH;
local inflate_huft fixed_mem[FIXEDH];
local uInt fixed_bl;
local uInt fixed_bd;
local inflate_huft *fixed_tl;
local inflate_huft *fixed_td;


local voidpf falloc(q, n, s)
voidpf q;        /* opaque pointer (not used) */
uInt n;         /* number of items */
uInt s;         /* size of item */
{
  Assert(s == sizeof(inflate_huft) && n <= fixed_left,
         "inflate_trees falloc overflow");
  if (q) s++; /* to make some compilers happy */
  fixed_left -= n;
  return (voidpf)(fixed_mem + fixed_left);
}


local void ffree(q, p, n)
voidpf q;
voidpf p;
uInt n;
{
  Assert(0, "inflate_trees ffree called!");
  if (q) q = p; /* to make some compilers happy */
}


local int inflate_trees_fixed(bl, bd, tl, td)
uIntf *bl;               /* literal desired/actual bit depth */
uIntf *bd;               /* distance desired/actual bit depth */
inflate_huft * FAR *tl;  /* literal/length tree result */
inflate_huft * FAR *td;  /* distance tree result */
{
  /* build fixed tables if not built already--lock out other instances */
  while (++fixed_lock > 1)
    fixed_lock--;
  if (!fixed_built)
  {
    int k;              /* temporary variable */
    unsigned c[288];    /* length list for huft_build */
    z_stream z;         /* for falloc function */

    /* set up fake z_stream for memory routines */
    z.zalloc = falloc;
    z.zfree = ffree;
    z.opaque = Z_NULL;

    /* literal table */
    for (k = 0; k < 144; k++)
      c[k] = 8;
    for (; k < 256; k++)
      c[k] = 9;
    for (; k < 280; k++)
      c[k] = 7;
    for (; k < 288; k++)
      c[k] = 8;
    fixed_bl = 7;
    huft_build(c, 288, 257, cplens, cplext, &fixed_tl, &fixed_bl, &z);

    /* distance table */
    for (k = 0; k < 30; k++)
      c[k] = 5;
    fixed_bd = 5;
    huft_build(c, 30, 0, cpdist, cpdext, &fixed_td, &fixed_bd, &z);

    /* done */
    fixed_built = 1;
  }
  fixed_lock--;
  *bl = fixed_bl;
  *bd = fixed_bd;
  *tl = fixed_tl;
  *td = fixed_td;
  return Z_OK;
}


local int inflate_trees_free(t, z)
inflate_huft *t;        /* table to free */
z_stream *z;            /* for zfree function */
/* Free the malloc'ed tables built by huft_build(), which makes a linked
   list of the tables it made, with the links in a dummy first entry of
   each table. */
{
  register inflate_huft *p, *q;

  /* Go through linked list, freeing from the malloced (t[-1]) address. */
  p = t;
  while (p != Z_NULL)
  {
    q = (--p)->next;
    ZFREE(z, p, p->word.Nalloc * sizeof(inflate_huft));
    p = q;
  } 
  return Z_OK;
}

/*+++++*/
/* infcodes.c -- process literals and length/distance pairs
 * Copyright (C) 1995 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h 
 */

/* simplify the use of the inflate_huft type with some defines */
#define base more.Base
#define next more.Next
#define exop word.what.Exop
#define bits word.what.Bits

/* inflate codes private state */
struct inflate_codes_state {

  /* mode */
  enum {        /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
      START,    /* x: set up for LEN */
      LEN,      /* i: get length/literal/eob next */
      LENEXT,   /* i: getting length extra (have base) */
      DIST,     /* i: get distance next */
      DISTEXT,  /* i: getting distance extra */